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• Split a movie so that each GIF is under a certain file size

  9 novembre 2014, par Terence Eden

  Problem

  I want to convert a long movie into a series on animated GIFs.

  Each GIF needs to be <5MB.

  Is there any way to determine how large a GIF will be while it is being encoded ?

  Progress So Far

  I can split the movie into individual frames :

  ffmpeg -i movie.ogv -r 25 frameTemp.%05d.gif

  I can then use convert from ImageMagick to create GIFs. However, I can’t find a way to determine the likely file size before running the command.

  Alternatively, I can split the movie into chunks :

  ffmpeg -i movie.ogv -vcodec copy -ss 00:00:00 -t 00:20:00 output1.ogv

  But I’ve no way of knowing if, when I convert the file to a GIF it will be under 5MB.

  A 10 second scene with a lot of action may be over 5MB (bad !) and a static scene could be under 5MB (not a problem, but not very efficient).

  Ideas

  I think that what I want to do is convert the entire movie into a GIF, then find a way to split it by file size.

  Looking at ImageMagick, I can split a GIF into frames, but I don’t see a way to split it into animated GIFs of a certain size / length.

  So, is this possible ?

• H264 decompression/decomposition into JPG - quality issues

  5 juin 2013, par Respectech

  I'm trying to decode a 1920x1080 30fps h264 stream. Individual frames look outstanding in VLC media player (pausing the playback), but when I decode using avconv (ffmpeg has been deprecated and replaced by avconv), the frame quality is really poor by comparison (my primary complaint is blockiness).

  Here's how I am calling avconv :

  avconv -i video.h264 -s 1920x1080 -f image2 temp/images/video-%03d.jpg

  Is there a jpg output setting for avconv ? I read what I suspected were the salient parts of the avconv documentation (namely, http://libav.org/avconv.html#image2-1), and couldn't find any way to specify the output jpg quality.

  In addition, it appears avconv reads the entire stream before it starts decoding it, so if the stream is in progress, it only decodes to where the stream was when avconv started the decoding process. Is there any way around this ? In other words, if a 10-second-long stream is started at t seconds and avconv is started at t+1 seconds, avconv will only decode 1 second of the stream.

• MP4Box Dash mpd not working

  7 décembre 2017, par Durlabh Sharma

  I’m trying to make a DASH client with Exoplayer as client on Android side. I am able to create individual Dash streams for audio or video. But I am unable to create a stream that includes both audio and video in single mpd file.

  For video, command used is :

  MP4Box -dash 4000 -frag 4000 -rap -segment-name segment_ ../video_enc.mp4#video

  For audio, command is :

  MP4Box -dash 4000 -frag 4000 -rap -segment-name segment_ ../video_enc.mp4#audio

  They both work perfectly fine. But when I go to create a single mpd, it creates mpd but it just doesn’t work. Even after creating all segments and fragments, it still fails to playCommand used is :

  MP4Box -dash 4000 -frag 4000 -rap -bs-switching no -profile dashavc264:live -segment-name segment_ ../video_enc.mp4#audio ../video_enc.mp4#video